Purification of Glyoxysomal Catalase and Immunochemical Comparison of Glyoxysomal and Leaf Peroxisomal Catalase in Germinating Pumpkin Cotyledons

Publisher Website
Google Scholar
Abstract
As a step to study the mechanism of the microbody transition (glyoxysomes to leaf peroxisomes) in pumpkin (Cucurbita sp. Amakuri Nankin) cotyledons, catalase was purified from glyoxysomes. The MW of the purified catalase was determined to be 230,000-250,000 daltons. The enzyme was judged to consist of 4 identical pieces of the monomeric subunit with MW of 55,000 daltons. Absorption spectrum of the catalase molecule gave 2 major peaks at 280 and 405 nm, showing that the pumpkin enzyme contains heme. The ratio of absorption at 405 and 280 nm was 1.0, the value being lower than that obtained for catalase from other plant sources. The pumpkin glyoxysomal catalase apparently contains a higher content of heme in comparison with other plant catalases. The immunochemical resemblance between glyoxysomal and leaf peroxisomal catalase was examined by using the antiserum specific against the purified enzyme preparation from pumpkin glyoxysomes. Ouchterlony double diffusion and immunoelectrophoretic analysis demonstrated that catalase from both types of microbodies cross-reacted completely whereas the immunotitration analysis showed that the specific activity of the glyoxysomal catalase was 2.5-fold higher than that of leaf peroxisomal catalase. Single radial immunodiffusion analysis showed that the specific activity of catalase decreased during the greening of pumpkin cotyledons.